July 2018, Vol. 245, No. 7


Memphis Utility Makes Big Inroads in 30-Year Replacement Plan

By Michael Reed, Managing Editor

As the largest three-service municipal utility in the United States, Memphis Light, Gas and Water (MLGW) faces a myriad of complicated decisions concerning the repair and maintenance of infrastructure throughout Shelby County, Tenn.

A TransCanada official said the company will start building the Coastal GasLink pipeline early next year, pending a positive final investment decision (FID) on the linked LNG Canada project.

Founded in 1939, among the company’s chief concerns is the safety of its gas distribution system, particularly the 330 miles of cast-iron gas mains it began replacing in 1992 as part of a $100 million program.

“Basically, we are removing pipe and any services that we came across that required replacement,” said Alonzo Weaver, vice president of MLGW’s Engineering and Operations Department. “There are some coupling issues, but overall, eliminating the cast-iron is the main focus.”

The overall effort calls for all cast-iron to be eliminated from the system by 2021. With about 10 miles of replacement work left to do on 10- and 16-inch pipes, this puts the company right on schedule.

Along with cast-iron replacement the company plans to eliminate all the wrought iron and PVC gas pipes from its gas distribution systems. This effort will be completed by 2021 as well. The wrought-iron still remaining in the system covers about 2 miles and consists of 2- and 4-inch mains. 

“MLGW eliminated all of its standard pressure system this fall, which was mainly cast-iron mains,” Weaver said. 

The first cast-iron mains addressed were in the company’s high-pressure system, which operates between 61 and 99 psig, and the medium-pressure system, which operates between 31 and 60 psig. These two systems were deemed to have the higher possibility of leaks. 

Next, MLGW focused on intermediate-pressure lines, which operate between 15 and 30 psig, and the company’s standard-pressure system, which operates at about one-quarter psig. 

As with other utilities in major cities, the company’s replacement and maintenance efforts require negotiating areas of congestion both above-ground (schools, three hospitals and a zoo, among them), and below-ground, within street rights-of-ways.

“The bigger challenge is within the neighborhoods themselves,” Weaver said. “Some of these are older communities, and you have to open up a series of holes out in the streets. These are pretty much one-lane, one-way streets that are made inaccessible.”

Some of these streets, where there were pockets of cast iron infrastructure dating back to 1956, were deemed to be among the highest priorities for the program. To avoid as much inconvenience as possible, the corporate communications department had to be proactive.

“It takes a lot of communications, and we put out letters on the timing of street closures, sometimes a month or two in advance,” Weaver said. “The work is very weather-driven, though. You can put out information a month in advance, but still have to follow up and deal with possible changes.”

When possible, if the work includes disconnecting services, MLGW tries to notify the customer through a letter to their home or business 14 days in advance. When that’s not possible at least seven days notice is given.

For road closures, the company notifies the local media and distributes the information through MLGW social media platforms.

In emergency situations, an auto-dialer sends a recorded message to the customer’s on-file phone number. In some cases, notices are distributed door-to-door.

Replacing older gas mains, a process that began in 1992

In order to limit the amount of digging required, MLGW uses horizontal directional drilling whenever possible. Additionally, guided-wave (GW) technology is used to detect anomalies and potential leaks within the transmission system.


The company also relies on steel service taps to integrate a transition from steel to polyethylene (PE), and uses excess flow valves into the tapping tees for new construction of services and gas distribution mains that have been replaced with steel.

“This fitting reduces the number of couplings needed to transfer the service to the new gas main. Only one coupling is needed to connect the service pipe to the tee,” Weaver said.

Some of the cast-iron replacement will rely on coated welded steel instead of PE, he added.

Weaver, who graduated high school in 1979, discovered his future career path in energy at a relatively young age. He worked as an intern in construction and maintenance at MLGW during the summer break while in college at Rensselaer Polytechnic Institute, in Troy, N.Y., where he earned a bachelor’s degree in mechanical engineering.

“I pretty much interviewed with utilities from that point going forward,” he said. “I found out there was a lot involved in getting electric, gas and water to the customers, and that it was pretty interesting work.”

MLGW, which employs about 2,600 people, has remained active in offering internships and maintaining a co-op program over the years, which Weaver said “has paid off very well for both us and for the students.”

Weaver joined MLGW in 1983 as an engineering assistant in Electric Operations and was promoted to operations assistant in that department in 1987. He completed the MLGW Executive Development Program in 1988 and received an MBA from the University of Memphis in 1997.

In his current position, Weaver is responsible for managing and coordinating all engineering functions, including commercial and residential engineering, as well as electric, gas and water operations. He is also responsible for water quality assurance and systems operations.

Weaver said the work has remained rewarding throughout his career, but that doesn’t mean his job doesn’t come with some stressful moments. In addition to gas operations, he is the “crisis management guy” on the electric side. That entails dealing with situations such as customer service outages and restoration efforts following storms.

“As far as gas is concerned, making sure we are on top of all the regulations and that we keep a safe system is my top concern,” he said. “Our gas operations have a tremendous safety record, but all it takes is one or two incidents to tarnish that. We realize we don’t have a lot of room for error on that.”

A Little History

While Memphis Light, Gas and Water has been in existence since 1939, its parent companies started well over 100 years ago, getting its start not long after the Civil War.

Memphis’ first utility company was the Memphis Gas Light Company, formed in 1852 and serving about 10,000 people in only a three-square-mile area. The “electric age” began at about that same time, ushering in the use of powered light, appliance and other home and business conveniences. To serve that need, Memphis Light and Power Company was formed.

In 1902, the company merged with the city’s only natural gas distributor, and by 1917, the city’s two competing gas and electric companies consolidated, eventually becoming Memphis Power and Light.

The city of Memphis bought privately owned Memphis Power and Light in 1939, and Memphis Light, Gas and Water was formed, creating what is now the largest three-service public utility in the nation. P&GJ

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